FIG. 1 is a view showing the structure of a compression line spring.
Generally, the compression line spring 10 is a spring that is manufactured by spirally winding a linear spring material. The compression line spring is processed through a seat-surface grinding process so that seat surfaces 10a and 10b formed on opposite ends of the compression line spring 10 are oriented perpendicular to a shaft S of the spring 10.
FIG. 2 is a plan view showing the construction of a conventional apparatus for grinding compression line springs. FIG. 3 is a side view showing the construction of the conventional grinding apparatus.
The conventional grinding apparatus includes a turntable 20 that rotates with a plurality of compression line springs 10 fixed to the turntable 20, and a plurality of grinding wheels 30 that are disposed above and below the turntable 20 and face each other with the turntable 20 disposed therebetween. The grinding wheels 30 grind the seat surfaces of the compression line springs 10 that are being transferred by the rotation of the turntable.
A plurality of installation holes 21 are formed in the turntable 20, and compression line springs are fitted into the installation holes 21. The installation holes 21 have diameters corresponding to outer diameters of the compression line springs to be ground so that the compression line springs can be reliably supported on the turntable while the operation of grinding the compression line springs is conducted.
However, the conventional grinding apparatus has the following problems.
When it is required in a separate operation to grind compression line springs having a different dimension, the entirety of the turntable must be replaced with another one. This makes the work complex. In addition, different kinds of turntables corresponding to the kinds of compression line springs must be prepared, thus increasing the cost of equipment.
That is, the installation holes formed in the turntable cannot be adjusted in diameter. Thus, it is impossible to install compression line springs having outer diameters greater than the diameter of the installation holes. In the case of compression line springs having excessively smaller outer diameters than the diameter of the installation holes, when the grinding process is conducted, the compression line springs cannot be reliably supported. Thus, vibrations may occur. Furthermore, there is the likelihood of the compression line springs being removed from the installation holes, which may lead to an accident.
Therefore, there is a problem in that the turntable must be replaced with another one when it is required to grind other kinds of compression line springs.